A new set of emerging films are being beneficially employed in the development of high density semiconductor chips such as for example high density DRAM. These materials provide for higher capacity devices by allowing a reduction in the size of the individual features on the memory device. Accordingly, enhanced selectivity and profile control are required.
In the past, ion mills, which are a slow physical process, have been used to establish desired profiles on semiconductor wafers. Such ion mills have disadvantages in that the profile formed on the semiconductor wafer is sensitive to the angle of the ion mill beam and thus, the ion mill beam has to be accurately positioned to obtain the required profile. When profiles are obtained, however, large veils or ribs sticking up from the edges of the desired profiles have been experienced. Accordingly, ion mills are not well suited to emerging films.
Plasma etch processes for use in emerging films are faster, however such processes can in some cases provide unacceptable feature profiles. Accordingly, there is a need to provide an etching process which quickly and accurately process the emerging films that are used in the latest semiconductor products.
The present invention is directed toward a plasma etch reactor which can successfully process emerging films used in high density semiconductor devices.
The present invention provides for a plasma etch reactor which has a reactor chamber and an upper electrode which is grounded, a lower electrode which is connected to high frequency power supply, and a low frequency power supply, and a peripheral or ring electrode which is positioned between the upper and lower electrodes. The potential for said peripheral or ring electrode is allowed to float. Alternatively, the ring electrode can be grounded. Such a reactor can successfully process the newest emerging films used in high density semiconductor products.
It is a further object of the present invention to provide the reactor chamber with magnets in order to produce a high magnetic field, and thus a sufficiently dense plasma in order to successfully etch the newest emerging films.
It is a further object of the present invention to have the densitv and etch characteristics of the plasma controlled by one or more of the power sources.